Place the sesame seeds in a dry heavy-bottomed saucepan over medium heat. Stir constantly for 3 to 4 minutes until golden and fragrant. Pour into a large heatproof bowl.

Add the desiccated coconut to the same bowl and stir to combine with the warm sesame seeds. Set aside.

Line an 8x8 inch baking pan with parchment paper and brush lightly with oil or melted butter. Set near the stove.

Combine the sugar, honey, butter, and salt in the same saucepan over medium heat. Stir until the sugar dissolves and the butter melts, about 2 minutes.

Stop stirring and clip a candy thermometer to the pan. Bring the syrup to 140 C (285 F), the soft-crack stage, which takes about 5 to 7 minutes. Watch closely as it can darken fast.

Remove from heat immediately. Stir in vanilla extract if using.

Pour the hot syrup over the sesame-coconut mixture in the bowl. Stir quickly with a wooden spoon until every seed and coconut shred is coated. Work fast, you have about 90 seconds before it stiffens.

Immediately scrape the mixture into the prepared pan. Press down firmly and evenly with the back of an oiled spoon or a second sheet of parchment placed on top. You want a slab about 1 cm (3/8 inch) thick.

Score the surface deeply with a sharp knife into 16 equal rectangles while the slab is still warm, pressing all the way through. This is the moment - do not skip it.

Leave the slab to cool and set at room temperature for at least 30 minutes. Once fully firm, snap along the scored lines and the bars will break cleanly.